The time frame during which
humans first reached the Americas remains hotly debated. One
key to settling this controversy would involve uncovering early
examples of human artifacts, such as art.

Scientists discovered one ancient sample of such art in a cave
named Lapa do Santo in central-eastern Brazil. The region is home
to
Luzia, the oldest human skeleton found to date in South
America.

Lapa do Santo is one of the largest rock shelters excavated yet
in the region, a limestone cave covering an area of about 14,000
square feet (1,300 square meters). Here, researchers have found
buried human remains, tools made of stone and bone, ash from
hearths, and leftovers from meals of fruit and small game.

In 2009, digging about 13 feet (4 meters) below the surface, the
scientists found a rock carving or petroglyph of a man packed
into the side of the cave. The figure, which appears to be
squatting with his arms outstretched, is about 12 inches (30
centimeters) tall from head to feet and about 8 inches (20
centimeters) wide. [ Photos
of Phallus Petroglyph and Cave ]

"We discovered this petroglyph in the final moments of excavation
at the site," said researcher Walter Alves Neves, an
archaeologist and biological anthropologist at the University of
São Paulo in Brazil.

"The figure is probably linked to some kind of fertility ritual,"
Neves told LiveScience. "There is another site in the same region
where you find paintings with men
with oversized phalluses, and also pregnant women, and even a
parturition (childbirth) scene."

Carbon dating and other tests of the sediment covering the
petroglyph suggest the engraving dates between 9,000 and 12,000
years old. This makes it the oldest reliably dated instance of
such rock art found yet in the Americas.

When this carving is compared with other examples of
early rock art found in South America, it would seem that
abstract forms of thinking may have been very diverse back then,
which suggests that humans settled the New World relatively
early, giving their art time to diversify. For instance, at one
site in Argentina named Cueva de las Manos, paintings of hands
predominate, while at another site there, Cueva Epullan Grande,
engravings have geometric motifs.

"It shows that about 11,000 years ago, there was already a very
diverse manifestation of rock art in South America, so probably
man arrived in the Americas much earlier than normally is
accepted," Neves said.

The scientists detailed their findings online Feb. 22 in the
journal PLoS ONE.